Teledyne manual RS-232 Cable Connections, Name Symbol Function

RS-232 Cable Connections

Commonly used DB9 / DB25 cable connections for EIA/TIA-232 and V.24 Asynchronous Interfaces.

DB9	DB25	NAME	SYMBOL	FUNCTION
1	8	Data Carrier Detect	DCD	Handshake from DCE
2*	3	Receive Data	RxD	Data from DCE
3*	2	Transmit Data	TxD	Data from DTE
4	20	Data Terminal Ready	DTR	Handshake from DTE
5*	7	Signal Ground	GND	Ground/Return
6	6	Data Set Ready	DSR	Handshake from DCE
7	4	Request to Send	RTS	Handshake from DTE
8	5	Clear to Send	CTS	Handshake from DCE
9	22	Ring Indicator	RI	Handshake from DCE

* Only pins used by API Multi-drop.

NOTE: Generally Asynchronous host equipment only requires the TxD, RxD and GND signals as indicated by the asterisk (*). If your host system requires certain handshake signals, you must wire back those signals to the corresponding handshake response lines. Wire host connectors as shown in the table below:

Host DB25 to M-drop DB9

HOST M-DROP

2	3
3	2
7	5
4 to 5	n/c
6 to 20	n/c
8	n/c
22	n/c

Signal

TxD/RxD

RxD/TxD

GND

RTS/CTS

DSR/DTR

DCD

RI

Host DB9 to M-drop DB9

HOST M-DROP

2	3
3	2
5	5
7 to 8	n/c
4 to 6	n/c
1	n/c
9	n/c

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